The present invention relates to an angle detector and more particularly to an angle detector for detecting a rotating angle of a shaft of an automatic transmission of a motor vehicle, for example.
The related angle detector 200 shown in FIGS. 11 to 14B is an angle detector for detecting a rotating angle of a shaft with respect to a transmission case of an automatic transmission of a motor vehicle, for example. The angle detector 200 includes a housing 204, a rotating member 206, a torsion coil spring 202, a magnetic sensor 208 and a permanent magnet 210.
The rotating member 206 is provided in the housing 204 so as to rotate about an axis C1 as a rotating center. The housing 204 is installed integrally on the transmission case of the automatic transmission and the rotating member 206 is integrally on the shaft of the automatic transmission. In this state, when the shaft rotates relative to the transmission case of the automatic transmission, the rotating member 206 is made to rotate relative to the housing 204. Then, by the permanent magnet 208 provided integrally on the rotating member 206 being detected by the magnetic sensor 208, a rotating angle of the shaft relative to the transmission case of the automatic transmission is detected.
The rotating member 206 is urged in its rotating direction by the torsion coil spring 202. One end portion of the torsion coil spring 202 enters a hole provided in the housing 204 so as to be installed integrally in the housing 204. The other end of the torsion coil spring 202 enters a fan-shaped recess portion 212 provided on the rotating member 206.
In the state shown in FIG. 11, the other end portion of the torsion coil spring 202 is situated in an intermediate position of the fan-shaped recess portion 212. Moreover, since there is exerted no external force on the torsion coil spring 202, the urging of the rotating member 206 by the torsion coil spring 202 is not implemented.
However, when the rotating member 206 rotates about the axis C1 in a direction indicated by an arrow A11a from the state shown in FIG. 11, the other end portion of the torsion coil spring 202 is brought into abutment with one side wall 212A of the recess portion 212. Then, when the rotating member 206 rotates further in the direction indicated by the arrow A11a from that state of abutment, the rotating member 206 is then urged in an opposite direction to the direction indicated by the arrow A11a (in a direction indicated by an arrow A11b). Similarly, when the rotating member 206 rotates about the axis C1 in the direction indicated by the arrow A11b from the state shown in FIG. 11, the other end portion of the torsion coil spring 202 is brought into abutment with the other side wall 212B of the recess portion 212, whereby the rotating member 206 is urged in the direction indicated by the arrow A11a. 
Note that as patent documents on the related art, there can be raised Patent Document 1 and Patent Document 2, for example.    [Patent Document 1] Japanese Patent Publication Number 2000-179681    [Patent Document 2] Japanese Patent Publication Number 2001-254812
Incidentally, in the related angle detector 200, the rotating range of the rotating member 206 is controlled by use of the torsion coil spring 202. However, the other end portion (a lug-like portion) of the torsion coil spring 202 is not in integral engagement with the rotating member 206. Consequently, in the state shown in FIG. 11, the rotating member 206 is not urged by the torsion coil spring 202, and hence, the rotating member 206 is made free relative to the housing 204. Then, seeking the home position of the rotating member 206 needs to be implemented forcibly by the software of a control unit of a vehicle (a motor vehicle), leading to a problem that the home position seeking operation of the rotating member 206 becomes complex.